Slip detecting device for motor vehicle mounted with automatic transmission

Abstract

Disclosed is a slip detecting device for a motor vehicle mounted with an automatic transmission. The slip detecting device is provided with a device for detecting a rotational speed of the specific part in a driving system, whereby occurrence of a driving wheel slip is detected based on the speed variation state in the rotational speed such as the gradient of variation in the output shaft rotational speed when shifting. Therefore, a driving wheel slip can be detected at a low cost, regardless of the accelerator pressed condition.

What is claimed is: 
     
       1. A slip detecting device for a motor vehicle mounted with an automatic transmission, said motor vehicle having a driving system, comprising: a rotational speed detecting means for detecting a rotational speed of a specific part in said driving system;   a shift detecting means for detecting a shift effected in said automatic transmission;   a speed variation state index computing means for computing an index of state of speed variation caused by the shift, based on said rotational speed of the specific part in the driving system detected by said rotational speed detecting means; and   a slip detection means for detecting occurrence of driving wheel slip according to the index of state of speed variation.   
     
     
       2. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 1, further comprising: a driving force changing speed detection means for detecting a changing speed in a driving force of said driving system; and   a slip detection forbidding means for forbidding said detection of the slip occurrence when the changing speed is great.   
     
     
       3. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 1, wherein, said speed variation state index means computes a gradient of variation in rotational speed of an output shaft of said automatic transmission when shifting, as said index of state of speed variation.   
     
     
       4. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 1, wherein, said speed variation state index means computes a shifting time required for rotational speed of an input shaft of said automatic transmission to change to synchronous rotational speed, as said index of state of speed variation.   
     
     
       5. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 1, wherein, said speed variation state index means computes a variation amount in rotational speed of an output shaft of said automatic transmission from the starting point of shifting to its completion, as said index of state of speed variation.   
     
     
       6. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 1, wherein, said speed variation state index means computes a variation amount in rotational speed of an input shaft from the starting point of shifting to its completion, as said index of state of speed variation.   
     
     
       7. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 1, wherein, said speed variation state index means computes a ratio of variation amount in rotational speed of an output shaft of said automatic transmission, to variation amount in rotational speed of an input shaft of said automatic transmission, as said index of state of speed variation.   
     
     
       8. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 2, wherein, said speed variation state index means computes a gradient of variation in rotational speed of an output shaft of said automatic transmission when shifting, as said index of state of speed variation.   
     
     
       9. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 2, wherein, said speed variation state index means computes a shifting time required for rotational speed of an input shaft of said automatic transmission to change to synchronous rotational speed, as said index of state of speed variation.   
     
     
       10. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 2, wherein, said speed variation state index means computes a variation amount in rotational speed of an output shaft of said automatic transmission from the starting point of shifting to its completion, as said index of state of speed variation.   
     
     
       11. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 2, wherein, said speed variation state index means computes a variation amount in rotational speed of an input shaft from the starting point of shifting to its completion, as said index of state of speed variation.   
     
     
       12. A slip detecting device for a motor vehicle mounted with an automatic transmission as claimed in claim 2, wherein, said speed variation state index means computes a ratio of variation amount in rotational speed of an output shaft of said automatic transmission, to variation amount in rotational speed of an input shaft of said automatic transmission, as said index of state of speed variation.